1. Technical Field
This invention relates to the cutting of food product. In particular it relates to a tensionable serpentine blade and blade assembly for cutting food product.
2. Background Art
Devices for cutting food products into slices are well-known in the art and typically comprise a stationary array of cutting knives with a means to propel the food product through the knife array. The food product may be conveyed through the knife array by entraining it in a fluid stream, or in the alternative may be conveyed by mechanical or pneumatic means. Alternately, food product may be conveyed by a hydraulic plunger.
A typical hydraulic food cutting apparatus in use today has a receiving tank filled with a hydraulic carrier fluid, usually water, into which food product is dumped. A food pump draws its suction from the receiving tank, and pumps carrier fluid and the suspended food product from the tank into a segment of tube. The tube aligns the food product within the hydraulic carrier fluid for impingement upon a cutter blade assembly. The stationary knife array typically includes a plurality of knife blades mounted parallel to each other. If the food product is to be cut into slices, only a single such array need be utilized. However, if the food product is to be cut into sticks, such as potatoes for french fries, two such arrays are utilized with the knives in one array extending generally perpendicular to the knives in the other array.
Cole, et.al., U.S. Pat. No. 5,343,623 Knife Assembly for Cutting a Food Product, discloses a knife blade having a cutting portion defining a cutting edge which is mounted in the knife assembly such that a tension force is exerted on the knife blade in the plane of the cutting edge. The cutting edges of knives in the array are located in a common plane. Cole, et.al, further discloses an apparatus for mounting the individual knife blades for applying the requisite tension to the individual blades.
There may be advantage in providing a tensionable serpentine blade and blade assembly which allows for the cutting of food product which renders a cut food product having a wedge cross sectional configuration.
There may be advantage in providing a tensionable serpentine blade and blade assembly which allows for the cutting of food product which renders a cut food product having a wedge cross sectional configuration that includes a device for sensing a failure or breakage of a tensionable serpentine blade.
The present invention is directed to a blade assembly including a tensionable serpentine blade. The blade assembly includes a blade head including a first return, a second return and a transecting passage connecting the first return and the second return. The blade head also includes a first end retainer for retaining a first end of the blade and a tensioning assembly including a second end retainer for retaining a second end of the serpentine blade, the tensioning assembly configured to apply a tension along the length of the blade. When positioned on the blade head, the blade includes a first end and a second end, a first bend, a second bend, a first leg segment connecting the first bend and the second bend, and a second leg segment connecting to and extending from the second bend.
The blade head defines an aperture through which food product is passed for cutting. The blade is mounted to the blade head by fixing a first end of the serpentine blade in the first end retainer, passing the second end across the aperture on a first plane, about the first return, through the transecting passage connecting the first return and the second return, about the second return, across the aperture again on a second plane and fixing a second end of the blade in a second end retainer. A tensioning member provides tensioning along the length of the blade. An assembly as described, when placed in use, will render a cut product having four segments, each segment having a wedge shaped cross-sectional configuration. The blade head may be configured to allow stacking of first and second blade heads, such that the second blade head is rotated 90xc2x0 to the first blade head. A stacked blade assembly, when placed in use, will render a cut product having eight segments each having a cut angle substantially equal to 45xc2x0.
The transecting passage is configured to permit passage of the serpentine blade from the first return to the second return such that a first leg of the serpentine blade lies across the aperture in substantially a first plane and a second leg of the serpentine blade lies across the aperture in substantially a second plane that lies substantially parallel to the first plane. The face of the first leg and the face of the second leg of the serpentine blade lie on intersecting planes such that, as a food product is passed through the aperture and across the first leg and the second leg of the serpentine blade, the food product is rendered to cut food product having a wedge shaped cross sectional configuration.
In one embodiment of the invention, various component parts of the blade head are machined of type 17-4 PH stainless steel, although other materials and forming methods known to those skilled in the art may be employed to practice the present invention.
In one preferred embodiment of the invention, the blade may be formed of a strip of sheet metal having a thickness of 0.005 inches to 0.0015 inches and a width of 0.375 inches to 0.625 inches. In one embodiment of the invention, the serpentine blade is formed of a hardened 301 stainless steel having a thickness of 0.008 inches and a width of 0.50 inches.
The material used to form the blade should exhibit adequate tensile strength to perform as a blade and adequate ductility to allow its continuous configuration. The material used to form the blade should also exhibit a yield strength less than the tensile strength. The blade may be formed of a strip of sheet metal having a tensile strength of 175,000 psi to 275,000 psi and a yield strength of 80,000 psi to 180,000 psi. In one embodiment of the invention, the blade is formed from a hardened type 301 stainless steel having a tensile strength of approximately 185,000 psi and a yield strength of approximately 140,000 psi.
Materials having compositions or properties similar to the hardened 301 series stainless steel, or 17-4 PH stainless steel, are known to those skilled in the art and may be employed in the present invention as a blade.
In one preferred embodiment of the invention, the tensioning member includes a tension adjustment screw disposed between the second end retainer and a fixed portion of the blade head.
In one preferred embodiment of the invention, the blade comprises a strip of material tensioned to a force approximating, but not exceeding, the yield strength of the material used to form the blade.
In one preferred embodiment of the invention, the first return and the second return each comprise a height substantially equal to a width of the blade configured to transfer a substantially equal tensile force across the width of the blade.
In one preferred embodiment of the invention, the first return and the second return each comprise a bearing face inclined at an angle in the range of 1xc2x0 to 10xc2x0.
In one preferred embodiment of the invention, the tensionable blade assembly includes a device for sensing a failure or breakage of a tensionable blade. The failure sensing device includes a fluid containment cell and a pressure release mechanism. The failure sensing device also includes a fluid pressure source fluidly connected to the fluid containment cell. The fluid containment cell may be configured as a cylinder formed in the cutting assembly head. The pressure release mechanism includes a stop which is configured to compressively mate against a seat formed in an aperture located in an end of the cylinder. When the stop is compressively mated against the seat, fluid will not escape from the fluid pressure chamber and pressure may be maintained within the chamber. The stop opposes the seat and cooperates with a compressive member for holding the stop against the seat of the fluid pressure chamber and sealing the fluid pressure chamber.